All .exe setup files deleted by avast when I double click

When I want to install any software & double click on setup file then a .tmp file is created in some random name & it is deleted suddenly by avast showing that it is infected by Win32:Malware-Gen. Before one day my system was infected by some virus & avast deleted it after boot-time scanning. After the removal of that virus avast deleting every .exe when double click on it.

Please Help me.

What does it report for the exe files as that sounds like sality or a file infector

Also what programme are you trying to install

At last I have to delete all the setup files present in my computer as all of them are infected by a Trojan.

Do you still require help ?

No I don’t need any help now. But in future same problem happen to someone then what he should do? Deleting all setup files is not the solution. As by this trojan all the .exe files present in the system are infected and avast can’t disinfect the exe files & only delete it. Is there any solution?

Is there any solution?
follow this guide and attach the logs then a removal expert will help you http://forum.avast.com/index.php?topic=53253.0